It is important to ensure that identification numbers are transmitted correctly and, in certain cases, not forged. If a UPC were scanned into a cash register incorrectly, the customer might be charged $10 for an item that should cost $1.50. Banks, which transfer money electronically many times a day, do not want to transfer money into the wrong account. This type of error does happen During the 1980s, Lt Col Oliver North, of Iran-Contra fame, gave US Assistant Secretary of State Elliot Abrams an incorrect Swiss bank account number for the purpose of depositing $10 million North gave Abrams an account number that began “368” whereas the correct number began “386”
Transmission errors can occur when bar codes are scanned incorrectly, when numbers are written or typed in the wrong order, or when other mistakes are made The most common types of errors that occur, based on a study presented in [26], are described below.
A single-digit error occurs when one of digits in the number changes to a different value 79 1% of all transmission errors that occur are single-digit errors.
A transposition-of-adjacent-digits error occur when two different side-by-side digits change places 10.2% of all the transmission errors that occur are transposition-of-adjacent-digits errors.
A jump-transposition error occur when two different digits, separated by a third digit between them, change places. Of all the transmission errors that occur, 0.8% of them are jump- transposition errors.
A twin error occurs when two identical side-by-side digits change to a different pair of identical digits. Of all transmission errors that occur, 0.5% them are twin errors”
A phonetic error occurs when two digits in the number, presented orally, are recorded incorrectly. For example, a person says “fourteen,” but the recorder hears “forty.” Of all the transmission errors that occur, 0.5% of them are phonetic errors.
A jump-twin error occurs when two identical digits, separated by a third digit between them, change to a different pair of identical digits. Of al transmission errors that occur, 0.3% of them are jump-twin errors.
Table 1.1 gives an example of each type of error, using six-digit identification number a_1 a_2 a_3 a_4 a_5 a_6 = 191433. Table 1.2 lists all of these types of errors along with their relative frequencies, as bases on a study presented in [26]. The lowercase letters a, b, and c represent single digits.